(S) From the RER C line Epinay sur Orge train station (Place Stalingrad), reach Rue Pasteur by crossing the tracks through the tunnel.
Continue on Rue Pasteur, pass by Rue de l’Orge on the right and Voie des Près to arrive on Rue de Corbeil (D117). Take it to the right for 100 m.
(1) Continue on a path that goes right along a stream. At the end of this path, do not turn right but continue on the path on the left that crosses the stream over a footbridge.
Go under the railway, pass by Avenue des Tilleuls as well as the path that continues along the stream. Also pass by Chemin Latéral and continue left across the path through a meadow to reach Rue de l’Orge.
(2) Turn right, cross the bridge and then go left and follow the banks of the Orge to the pond of Moulin du Breuil.
Cross the bridge on the left and go around the pond on the left. Come back to the footbridge, head left via Rue de Villemoisson, Rue de Rivoli and Rue de Chevreuse. At the end of the latter, turn right and immediately left to head up Rue de la Montagne.
(3) Turn left up Chemin des Froids Culs, then reach Rue de Rivoli. Head right for 200 m, return to the path and turn right on Chemin de Villiers in Epinay. At the next junction head opposite on Chemin de la Tournelle. Go to the entrance of Ballainvilliers. Go around the roundabout to the right, cross the D186 to the left as soon as possible and continue left on the road.
(4) At Rue Saint-Sauveur, turn right on Chemin d’Aunette then continue straight along the Bois des Templiers.
(5) Enter the woods on the right and follow the Rouillon on its left bank passing over Pont des Templiers bridge, a relic of eleventh century. On leaving the wood, turn right then up to the left on Rue de la Chevauchée Cut across Route de Corbeil road then right on Chemin de la Chevauchée as far as the railway line. Turn left and follow it until the Gravigny-Balisy station. Cross the level crossing to the right and continue for 10 m.
(6) Turn right on the GRP marked in red and yellow along the Yvette. We find the Rouillon, which flows into the river at this point. Arrive at the Petit Vaux station and head right on the street of the same name and cross at the level crossing. Turn left on Rue de la Station, which becomes a cycle path.
Cut across Rue du Grand Vaux to the left and take Rue des Rossay. Return to the GRP route on the right along Allée des Rossay taking you back to the station of the RER C Epinay sur Orge line.
